Tuesday, 2 April 2013

Lighting the way to energy savings

Uniform illumination courtesy of CREE
When specifying optimal luminaires for a forecourt design project, you would assume a higher power lighting fixture offers better subject illumination and visibility for safe circulation. However, a lower power solution offering more even uniform light can outperform some of the more powerful light fixtures. How is this possible you might wonder?

Take a stroll under natural moonlight. With an unobstructed view of the night sky, the scene before you will be remarkably apparent with just 1 lux. Compared with other artificial light emitting sources this level is astonishingly low thanks to the moon's ability to refract light.

Of course safety requirements for illuminating a public area necessitates a higher minimum lux luminaire. Furthermore, when deciding upon the most appropriate level of lighting, you have to carefully weigh up the following factors, for example: to what extent is visual attractiveness, comfort and security important for my project? What are the performance requirements the luminaires need to achieve? What visual function does the lighting needs to perform? To what degree must the lighting integrate with the surrounding architecture?

The amount of light required on a road to reveal objects (i.e. vehicles, pedestrians and obstructions) depends upon the average rate, density and speed of traffic, and whether pedestrians are typically present, i.e. mixed usage areas.

In the UK, there isn't a specific standard detailing how to light a petrol station forecourt, the only real guideline is BS EN 12464-2 Light and Lighting – Outdoor Workplaces, which only details a minimum of 150 lux.

Application 
Lighting Level   
Example
Under canopy lighting    400-500 lux
On face of pumps >100 lux
Area/Yard lighting 20 lux Heavy traffic, larger complex parking  

10 lux Medium traffic, major store parking

5 lux Light traffic, small shop parking

All things considered, low level diffused light still has considerable potential for excellent illumination, whilst high power point source light may be wasted.

Low lux even distributed light offers a cheaper, more sustainable and energy efficient solution as well as helping your client to minimize their installation costs.

The current trend is towards LED yard lamps where the fitting has been designed to give a wide angle dispersed light output. This solution, which combines the benefits of low energy consumption (and long life) with low lux even distributed light, offers the best of all worlds.

Although initial investment costs may be higher at start, there is typically a return on investment within two years and over lifetime, costs will be considerably lower.
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